Process for producing diketen



Patented 0... 1, 15 2 21 450 1 Martin human and Johann-Silt, Mllllich, Ger; many; assignors to Consortium fur ,Elelrtrochemische--Industrie, G.' m. b. IL, Munich,

Bavaria, Germany, a corporation ofGermany 'No Drawing; Application March 4, 1938, Serial invention relates -to the production of I diketen and has for its object to provide improvedprocess'for this purpose. i ,l J The productionief diket'enfrom pure keten theie'ss necessary'tofprevent boiling at the elevated temperatures at which the -reaction proceeds more rapidly;

The, point of. greatest vdifllculty, however, is

' that'rea'ction inithe'neighborhobd of 0 C. is very turbulent; while primarily higher polymerization products are formed. (Journal Chemical Society, London, 93, I, page 946 (1908); 9'7, II, page In another process acetone is used 1984 (i910) as solvent, and, while it is true that inthis case the output is better, this is true only when definite and precise instructions are followed in connection with the adjustment of the temperature whichmust be increased graduallywith increasing' conversion. The diketen which is thus generated must finally be separated from the acetone.

We have found that the disadvantages of former processes are avoided and that diketen can be produced in rapid reaction and with a good reaction liquid and the cooling medium. The process may also be performed without an excess of keten, for. example by supplying the keten at the lower end of a tall cylindrical vessel which 'may be cooled, and which is. filled with diketen.

this vessel beingsubdivided into sectionsfor the purpose of avoiding mixing, so thatthe saturated solution' formed below may enter into the reaction on the ';-top,o f theyvessel. "z The diketen involves yonsiderable technical diflicultie's,"due flows ofl"continuously"- at=the upper end ofthe "5- particularly to the; fact that the polymerization vessel, at.a.velocity such thatit leaves :thevessel occursat serviceable speed only in the"liqiii'dsubstantially ;f1 ee ,of keten. The diketen may phase while keten boils at ordinarypressureat .also be,treated with keten inacoolable stirring a. 1 1 Q., a temperature at which polymerization "boilen' The keten is absorbed by the diketen'in occurs onlyyer slowly. High pressure is neveri0 age proportion .91 ..its conversion. into diketen. p 'eeonv'ersion still-gives a good "output even. at

' aflt'empi'atureofbo". C. and over.

f.,-T 1he,1 d il;eten formation may be. substantially" acceleiafd fwith 'the use of elevated pressure which; increa esi'th'e saturation concentration of I5" theketen. "Ana'ddition of'a small quantity of 1 mineral acid or its acetyl compound to'neutralize noxious base traces has been found efiectiv e.

.acid vapor under vacuum and then condensed by being cooled to a low temperature. It was thereupon evaporated at ordinary, pressure and the steam was introduced in excess-at the bottom of an elongated vessel of Jena glass, of cylindrical form, filled with 100 parts of diketen,- the temperattireof which'was kept at C. by

The original quantity of diketen-100 partsincreased in the course of an hour by about 8-9%.' Impurities of 11% remained after vacuum-dis- 4 tilling the product, in proportion to the diketen which had been formed. -65

output without the use of particularly low temcooling. 15 'parts of diketen were formed in the so peratures, higher pressures or special solvents, if first hour, and the quantity increased proporsolutions of keten in diketen areieft to them tionally in the subsequent hours. The keten flow selves while conducting away the reaction heat. was stopped after six hours and the fiuidwas In such case the keten polymerizes with surpris allowed to stand another short period at 25 C.

ing rapidity in the diketen solution. The essen- The small residue of keten-which still remained 35 tialpoint in the principle of operation of our at that time 'wasevaporated into thevacuum 1 process is therefore that the polymerization is chamber of the keten-producing appliance and eifected from the very beginning in the presence the untreated diketen, of which altogether 205 of diketen. grams were available, was distilled in vacuum at 40 In performing pur process it isadvisable to the temperature of the boiling water-bath. ,The 40 keep the keten content of the diketen solution remaining residue which'consisted of polymerizain the vicinity of saturation by continuously suption'products of higher molecular value amounted plying fresh keten, in order to maintain the maxto 10% in proportion to the newly formed diketen.

- imuni speed of transformation. For instance, an Eiample excess of keten is conducted through diketen, 45

which is keptin a tall cylindricalvessel, while The operation was performed in substantially the temperature is kept, by cooling, at a pointat the same way as in Example 1... 1% acetyl.-chlo' which the speed of the diketen formation has the ride was added to the diketen and the temperadesired value, said speed being recognizable by ture maintained at C. There was a reflux 50- the resulting temperature difierence ,between the cooler in the gas chamber of the glass cylinder. 50

Exam le 3.

' 5 and 8% nickel. While maintaining a temperature of +10 C. and an overpressure of 1 atmosphere, liquid keten cooled to a low temperature was supplied from a pressure vessel in small por tions at the bottom of the cylinder. About 50 10 parts of diketen were newly formed in one hour;

The quantity of the by-products amounted to about 9% of the diketen yield.

It will be evident that various changes may be made in the details and methods of operation described above without departing fromthe scope and spirit of the invention as defined in the appendedclaims. k

The invention claimed is: I 1. Process for producing diketen from keten,

so which comprises introducing keten into substantially undiluted diketen and polymerizing the keten in the presence of the diketen while removing the reaction heat. g

2. Process for producing dlketen from keten, which comprises introducing keten into substantially undiluted dik'eten and polymerizing the keten in the presence of the diketen while maintaining the reaction mixture at a temperature of 3. Process for producing diketen from keten, which comprises continuously introducing keten into substantially undiluted diketen at a pressure above atmospheric pressure while continuously which comprises continuously introducing keten into substantially undiluted diketen at a temperature of 10-50 C.

5. Process for producing diketen from keten,

which comprises continuously introducing keten 8 into diketen in an elongated reaction chamber at a temperature of 10-50 C. and at a velocity such as to cause the diketen to leave said oham substantially free of keten.

6. Process for producing di ketenfrom keten, 0

which comprises introducing keten into substanq tially undiluted diketen and polymerizing the keten in the presence of the dilreten at a pressure between about 1 and 2 atmospheres absolute while maintaining the reaction mixture at a tempera- 15 ture. of 0 C. to 50 C.

7. Process for producing diketen from kete which comprises continuously stirring substantially undiluted diketen with keten at a temperature above 0 C., and at a pressure between about 1 and 2 atmospheres absolute, while removing the heat produced by the reaction.

8. Process for producing diketen from keten which comprises continuously introducing keten into substantially undiluted ,diketen at a pressure above atmospheric but not substantially greater I than 2 atmospheres absolute while continuously removing the heat produced by the reaction.

9. Process for producing diketen from keten which comprises continuously introducing substantially undiluted keten into diketen at a tem-' perature of 10 C. to 50C. and at a'pressure between about 1 and 2 atmospheres absolute.

35 removing the heat producedby the reaction.

. 4,. Process for producing diketen from keten, JOHANN SIXT.

- mm MUGDAN; 

